First-principles prediction and partial characterization of the vibrational states of water up to dissociation

Császár, Attila G.; Mátyus, Edit; Szidarovszky, Tamás; Lodi, Lorenzo; Zobov, Nikolai F.; Shirin, Sergei V.; Polyansky, Oleg L.; Tennyson, Jonathan

doi:10.1016/j.jqsrt.2010.02.009

Cited by 76 publications

(74 citation statements)

References 68 publications

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“…114,165 These experiments have the major advantage over the neardissociation experiments on H + 3 that their multiphoton nature both greatly simplifies the resulting spectrum and makes the assignment of the rotational quantum numbers to the final state relatively straightforward. Variational calculations on the bound levels gives good general agreement 166 with the observations although the differences increase markedly just below dissociation suggesting that the PES in this region is less accurate than at lower energies. Thus far global water potentials have not included the effect of spin-orbit coupling, 167 which is known to be unimportant at low energies 168 but almost certainly becomes significant near dissociation.…”

Section: Future Directionssupporting

confidence: 58%

Perspective: Accurate ro-vibrational calculations on small molecules

Tennyson

2016

The Journal of Chemical Physics

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In what has been described as the fourth age of quantum chemistry, variational nuclear motion programs are now routinely being used to obtain the vibration-rotation levels and corresponding wavefunctions of small molecules to the sort of high accuracy demanded by comparison with spectroscopy. In this perspective, I will discuss the current state-of-the-art which, for example, shows that these calculations are increasingly competitive with measurements or, indeed, replacing them and thus becoming the primary source of data on key processes. To achieve this accuracy ab initio requires consideration of small effects, routinely ignored in standard calculations, such as those due to quantum electrodynamics. Variational calculations are being used to generate huge lists of transitions which provide the input for models of radiative transport through hot atmospheres and to fill in or even replace measured transition intensities. Future prospects such as the study of molecular states near dissociation, which can provide a link with low-energy chemical reactions, are discussed. Published by AIP Publishing. [http://dx

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Section: Future Directionssupporting

confidence: 58%

Perspective: Accurate ro-vibrational calculations on small molecules

Tennyson

2016

The Journal of Chemical Physics

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“…These energies for H 2 O fortunately exist up to dissociation and these are the ones we use. 34 Figure 3 shows that 1GB-EQ can reconstruct the classical vibrational energy distribution in an excellent way. The unphysical tail above the threshold energy is not present and, as opposed to the classical distribution, there is no violation of the zero-point energy (0.575 eV).…”

Section: Theoretical Details and Tests Of Binning Methodsmentioning

confidence: 96%

A novel Gaussian Binning (1GB) analysis of vibrational state distributions in highly excited ${\rm H}_\text{2}$H2O from reactive quenching of OH* by ${\rm H}_\text{2}$H2

Conte

Kamarchik

et al. 2013

The Journal of Chemical Physics

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As shown in experiments by Lester and co-workers [J. Chem. Phys. 110, 11117 (1999)], the reactive quenching of OH* by H 2 produces highly excited H 2 O. Previous limited analysis of quasiclassical trajectory calculations using standard Histogram Binning (HB) was reported [B. Fu, E. Kamarchik, and J. M. Bowman, J. Chem. Phys. 133, 164306 (2010)]. Here, we examine the quantized internal state distributions of H 2 O in more detail, using two versions of Gaussian Binning (denoted 1GB). In addition to the standard version of 1GB, which relies on the harmonic energies of the states (1GB-H), we propose a new and more accurate technique based on exact quantum vibrational energies (1GB-EQ). Data from about 42 000 trajectories from previous calculations that give excited water molecules are used in the two versions of 1GB as well as HB. For the vibrationally hot molecules considered in this study, the classical internal energy distribution serves as a benchmark to estimate the accuracy of the different binning methods analyzed. The 1GB discretization methods, especially the one using exact quantum energies, reconstruct the classical distribution much more accurately than HB and also the original, more elaborate Gaussian Binning method. Detailed quantum state distributions are presented for pure overtone excitations as well as several antisymmetric stretch distributions. The latter are focused on because the antisymmetric stretch has the largest emission oscillator strength of the three water modes. © 2013 AIP Publishing LLC. [http://dx

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“…Ab initio studies of small polyatomic molecules emerged in the past decades with drastically improved computational methods and hardware resources. A breakthrough in predicting rotationally resolved spectra of small molecules was made possible by accurate electronic structure calculations of the molecular PESs and DMSs (see, e.g., Partridge & Schwenke 1997;Cours et al 2002;Yurchenko et al 2009;Nikitin et al 2009;Lodi et al 2011;Császár et al 2010;Szalay et al 2011;Huang et al 2011aHuang et al , 2012Sousa-Silva et al 2014;Nikitin et al 2014;Li et al 2014;Delahaye et al 2015) and by developing efficient methods for quantum nuclear motion calculations (see Schwenke & Partridge 2001;Schwenke 2002;Cassam-Chenaï et al 2012;Yurchenko et al 2007;Wang & Carrington Jr. 2013a,b;Carter et al 2009;Rey et al 2012;Bowman et al 2005). In case of triatomics, such as water isotopic species (Yurchenko et al 2009;Barber et al 2011), carbon dioxide (Huang et al 2013(Huang et al , 2014, and ozone accurate theoretical predictions led to significant extensions of spectral analyses toward higher energy ranges.…”

Section: Theory and Computational Methodsmentioning

confidence: 99%

First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

Rey

Delahaye

Nikitin

et al. 2016

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We present the construction of complete and comprehensive ethylene line lists for the temperatures 50−700 K based on accurate ab initio potential and dipole moment surfaces and extensive first-principle calculations. Three lists spanning the [0−6400] cm −1 infrared region were built at T = 80, 160, and 296 K, and two lists in the range [0−5200] cm −1 were built at 500 and 700 K. For each of these five temperatures, we considered possible convergence problems to ensure reliable opacity calculations. Our final list at 700 K was computed up to J = 71 and contains almost 60 million lines for intensities I > 5 × 10 −27 cm/molecule. Comparisons with experimental spectra carried out in this study showed that for the most active infrared bands, the accuracy of band centers in our theoretical lists is better on average than 0.3 cm −1 , and the integrated absorbance errors in the intervals relevant for spectral analyses are about 1−3%. These lists can be applied to simulations of absorption and emission spectra, radiative and non-LTE processes, and opacity calculations for planetary and astrophysical applications.

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First-principles prediction and partial characterization of the vibrational states of water up to dissociation

Cited by 76 publications

References 68 publications

Perspective: Accurate ro-vibrational calculations on small molecules

Perspective: Accurate ro-vibrational calculations on small molecules

A novel Gaussian Binning (1GB) analysis of vibrational state distributions in highly excited ${\rm H}_\text{2}$H2O from reactive quenching of OH* by ${\rm H}_\text{2}$H2

First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

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First-principles prediction and partial characterization of the vibrational states of water up to dissociation

Cited by 76 publications

References 68 publications

Perspective: Accurate ro-vibrational calculations on small molecules

Perspective: Accurate ro-vibrational calculations on small molecules

A novel Gaussian Binning (1GB) analysis of vibrational state distributions in highly excited ${\rm H}_\text{2}$H2O from reactive quenching of OH* by ${\rm H}_\text{2}$H2

First theoretical global line lists of ethylene (12C2H4) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

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First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres